Use of naphthenic amines in phosphate flotation



United USE OF NAPHTHENIC AMINES IN PHOSPHATE FLOTATION ApplicationNovember 18, 1954 Serial No. 469,836.

2 Claims. (Cl. 209-166) No Drawing.

The present invention relates to the flotation separation of silicagangue from valuable phosphate rock employing as cationic reagents theamines derived from both high and low boiling naphthenic acids. It is,therefore, an object of the present invention to provide a process offlotation separation of phosphate rock involving the use of naphthenicamines prepared from naphthenic acids.

Large volumes of phosphate rock have been beneficiated by cationicflotation. Long chain fatty amines have been used principally in theseoperations. The present invention involves the use of naphthenic aminesfor this purpose, the naphthenic amines possessing advantages over thefatty amines used heretofore.

The naphthenic acids from which the naphthenic amines are prepared, areobtained as sludges from the refining of petroleum with sulfuric acidand caustic. The naphthenic acids are a complex mixture of compounds andinclude both mono and bicyclic compounds. There is considerablevariation in the boiling points of these acids depending upon themolecular weight. In general the naphthenic acids containing from 8 to12 carbon atoms are predominantly monocyclic in structure and arerelatively low-boiling. The acids containing from 13 to 22 carbon atomsare predominantly bicyclic and, accordingly, have higher boiling points.All of the compounds included in the general term naphthenic acids areuseful for the preparation of amines and the amines useful for phosphateflotation.

The naphthenic amines may be prepared from the naphthenic acids by theconventional method employed for the preparation of the fatty amines.This generally involves the formation of the nitrile from the acid andthe reduction of the nitrile to the amine either through conventionalhydrogenation or by means of sodium reduction. The naphthenic aminespossess the hydrophobic ring structure and the hydrophilic amine groupand are, therefore, especially desirable as silica collectors.

The naphthenic acids are low-priced by-products from petroleum refiningand, accordingly, the naphthenic amines are potentially very low incost. In addition, they possess advantages in their physical properties.In general they are readily dispersible liquids and, therefore, can bedispersed in an aqueous medium for the flotation process without anyparticular difliculty. The fatty amines on the other hand are generallymore difiicult to disperse and require conversion to a more soluble formsuch as by neutralization with organic or mineral acids.

The naphthenic amines may be employed in the concentrationsconventionally employed in flotation. Generally from 0.1 to 0.5 lbs. ofthe naphthenic amine per ton of ore is sufllcient.

EXAMPLE 1 Five hundred parts of a Florida pebble phosphate ore, assaying69.7% BPL and 12.2 HCl insolubles was conditioued at high percent solidswith 0.4 pound per ton of sodium hydroxide, 0.31 pound per ton ofnaphthenic aterit O amine (mean molecular weight 303), and 0.3 pound perton of pine oil. The pulp was transferred to a Fagergren flotationmachine, air introduced, and the silica tailing removed as froth. Noattempt to clean the flotation products was made. The results are shownin Table I.

Table I Phosphate Concentrate Silica Tailing Percent BPL Per- Per- BPLPercent Per- Per- BP L Recent cent Units H01 cent cent Units eovery Wt.BPL Insol. Wt. BPL

EXAMPLE 2 The procedure of Example 1 was repeated using 0.32 lb. per tonof naphthenic amines having a mean molecular weight of 350. The resultsare shown in Table II.

Example 1 was repeated, but 0.37 lb. per ton of naphthenic amines ofmean molecular weight 404 were used. The flotation results are shown inTable III.

Table III Phosphate Concentrate Silica Tailing Percent BPL Per- Per- BPLPercent Per- Per- BP L Recent cent Units H01 cent cent Units covery Wt.BPL Insol. Wt. BPL

All three of the above examples reveal the excellent ability of thenaphthenic amines to remove silica from phosphate. Example 2 showed theexcellent results in terms of highest grade and lowest content of HClinsolubles for the concentrate. In addition to the excellent performanceof these amines for flotation they are potentially very inexpensive andalso possess the requisite physical properties to make them readilydispersible without neutralization or further chemical modifiction.

Now, therefore, we claim:

1. A process for the treatment of phosphate ore for the separation ofphosphate minerals from pulp mixtures containing the same together withsilica and other impurities, which comprises adding to the pulp a smallamount of a naphthenic amine, subjecting the mixture to a frothflotation operation, separating silica and other impurities as froth andrecovering the phosphate minerals in the underflow.

2. A process according to claim 1 in which the naphthenic amine isemployed in the ratio of about 0.1 to 0.5 pound per ton of ore.

References Cited in the file of this patent UNITED STATES PATENTS2,217,685 Kirby Oct. 15, 1940

1. A PROCESS FOR THE TREATMENT OF PHOSPHATE ORE FOR THE SEPARATION OFPHOSPHATE MINERALS FROM PULP MIXTURES CONTAINING THE SAME TOGETHER WITHSILICA AND OTHER IMPURITIES, WHICH COMPRISES ADDING TO THE PULP A SMALLAMOUNT OF A NAPHTHENIC AMINE, SUBJECTING THE MIXTURE TO A FROTHFLOTATION OPERATION, SEPARATING SILICA AND OTHER IMPURITIES AS FROTH ANDRECOVERING THE PHOSPHATE MINERALS IN THE UNDERFLOW.